1.2 Mile Long Flushing Tunnel Pumps Millions of Gallons of Highly Oxygenated Water from New York Harbor to Head of the Canal
$158 Million Project is Key Component of Plan to Improve the Health and Cleanliness of the Gowanus Canal.
Department of Environmental Protection Commissioner Carter Strickland recently announced that the Gowanus Canal Flushing Tunnel will be re-activated for the first time since it was shut down for a full rehabilitation in 2010. The activation of the first submersible turbine pump will bring up to 100 million gallons of oxygen-rich water to the head of the Canal each day. The rehabilitation work also included draining the 1.2 mile long, 12 foot diameter tunnel and inspecting and repairing its brick-lined interior. After Hurricane Sandy, construction plans were altered to include resiliency measures such as raising the control room floor and its critical electrical equipment, flood-proofing the service building, and installing a dike wall and mechanical flood gate. Early next year it is expected that two additional turbine pumps will be activated, allowing for the injection of as much as 252 million gallons of fresher water into the Canal each day, or roughly 30 percent more than it could before the upgrade. In addition, the tunnel will operate around the clock, including at low-tide, when the Canal water is at its most stagnant. The system of three pumps provides redundancy that will ensure that the tunnel remains operational during future maintenance and repairs and the fresher water provided through the flushing tunnel will increase the dissolved oxygen content of the water in the Canal which will dramatically improve its aesthetics and provide a more suitable habitat for plant and aquatic life.
“Mayor Bloomberg has led a transformation of the city’s waterways and the re-activation of the flushing tunnel will significantly improve water quality in the Gowanus Canal,” said DEP Commissioner Strickland. “We will also install hundreds of curbside gardens and high level storm sewers in the surrounding neighborhoods and the re-activation of an important pump station will all help to improve the health and aesthetics of the Canal.”
"Cleaning up the Gowanus Canal has long been a priority for our community and we are happy that the flushing tunnel will be reopened and can start to improve water quality in the canal,” said City Council Member Brad Lander. “I look forward to working with Department of Environmental Protection to take the further steps necessary to make the Gowanus safe for our community."
“A clean and healthy Gowanus Canal will help ensure that the communities surrounding the Canal are safer, more sustainable, and aesthetically pleasing,” said City Council Member Stephen Levin. “I want to thank Commissioner Strickland and the Department of Environmental Protection for these improvements and their work to re-active the Gowanus Canal Flushing Tunnel.”
“The progress we’ve made over the last decade in cleaning up our waterways is one of the greatest accomplishments we as a city have made in ensuring the future health and well-being of all New Yorkers. The re-opening of this vital Gowanus Canal Flushing Tunnel puts one of the city’s most polluted waterways on a permanent path towards a more aesthetically pleasing and ecologically vibrant future. I want to thank Mayor Bloomberg for his leadership in our quest for a more environmentally sustainable and resilient New York and Commissioner Strickland for his excellent work on this project, and many others,” said Council Member James F. Gennaro, chair of the Council’s Committee on Environmental Protection.
“The reactivation of the Gowanus Canal flushing tunnel is yet another example that the clean-up of the canal is well underway,” said NYS Assembly Member Joan L. Millman. “I thank DEP for both repairing the flushing tunnel as well as increasing its capacity. Along with the EPA clean-up of the superfund site, we are another step closer to achieving a clean waterway.”
“I am very happy that the DEP will be returning the Flushing Tunnel to service,” said NYS Senator Velmanette Montgomery. “This, along with the EPA’s continuing cleanup of the Gowanus Canal, will literally breathe life into our beloved waterway!”
When the flushing tunnel was taken off-line in 2010, a temporary oxygen transfer system was installed alongside the Canal to help maintain a minimum level of oxygen in the stagnant water while the rehabilitation work took place. Removal of this temporary system could begin in January, once operational testing of the first flushing tunnel turbine pump is complete. The startup of the flushing tunnel for the first time in more than three years is also expected to temporarily stir up mud from the floor of the Canal, which will likely be visually noticeable. DEP has worked in conjunction with the NYS Department of Environmental Conservation (DEC) and US Environmental Protection Agency to draw up plans to mitigate this expected increase in turbidity by slowly raising the volume of water pumped into the Canal and installing silt curtains to catch suspended sediment at the head of the Canal. Water sampling and visual monitoring will also take place. The rehabilitation is proceeding pursuant to the federal Clean Water Act and a Consent Order entered into by DEP and DEC that aims to improve water quality throughout New York Harbor.
The Gowanus Canal is a nearly two mile long man made waterway that was built in the 1860’s to facilitate commerce in western Brooklyn. The Canal runs from New York Harbor northeast through the Red Hook, Carroll Gardens, and Park Slope neighborhoods where it dead ends at Butler Street. Over time, commerce in the area grew but the Canal and its environs were left with a legacy of industrial contamination. In addition, with limited natural movement of water, the Canal became a stagnant and polluted waterway.
In 1911, the Gowanus Canal Flushing Tunnel was built to pump polluted water from the head of the Canal to Buttermilk Channel, which is part of the East River and lies between Governors Island and the Red Hook neighborhood of Brooklyn. After decades of use and upgrades, the tunnel was taken out of service in the 1960’s and the Canal remained stagnant for the next 30 years. DEP began a rehabilitation of the Flushing Tunnel in 1994 and this work included reversing the flow, so that more oxygenated water was now pumped from Buttermilk Channel to the head of the Canal and the lower quality water was flushed out. The tunnel was re-activated in 1999 and with clearer, more oxygenated water, within months schools of fish and blue crabs had returned to the Canal.
As part of the overall effort to improve the health and cleanliness of the Gowanus Canal, DEP will install separate storm sewer pipes, or high-level storm sewers, along 3rd Avenue in Park Slope. Once completed, this project will keep millions of gallons of stormwater out of the combined sewer system, help to mitigate chronic flooding during heavy rain storms, and reduce sewer overflows into the Canal.
In addition, as part of the $1.5 billion Green Infrastructure Plan, beginning next spring DEP will build hundreds of specially engineered curbside gardens, or bioswales, in sidewalks throughout the neighborhoods surrounding the Canal. Each bioswale can absorb nearly 2,500 gallons of stormwater when it rains which eases pressure on the combined sewer system and helps to reduce overflows into the Canal. Bioswales also have hardy plants and trees to help absorb the stormwater, which also beautify the neighborhood, provide shade during the warmer months, and help clean the air.
DEP manages New York City’s water supply, providing more than one billion gallons of water each day to more than nine million residents, including eight million in New York City. The water is delivered from a watershed that extends more than 125 miles from the city, comprising 19 reservoirs and three controlled lakes. Approximately 7,000 miles of water mains, tunnels and aqueducts bring water to homes and businesses throughout the five boroughs, and 7,500 miles of sewer lines and 96 pump stations take wastewater to 14 in-city treatment plants. DEP has nearly 6,000 employees, including almost 1,000 in the upstate watershed. In addition, DEP has a robust capital program, with a planned $14 billion in investments over the next 10 years that will create up to 3,000 construction-related jobs per year. This capital program is responsible for critical projects like City Water Tunnel No. 3; the Staten Island Bluebelt program, an ecologically-sound and cost-effective stormwater management system; the city’s Watershed Protection Program, which protects sensitive lands upstate near the city’s reservoirs in order to maintain their high water quality; and the installation of more than 820,000 Automated Meter Reading devices, which will allow customers to track their daily water use, more easily manage their accounts and be alerted to potential leaks on their properties.
1. Sole reference for story was www.nycdep.gov.